Small and medium-sized boiler transformation: Standardized design of modular magnesium hydroxide desulfurization device
I. Industry pain points and transformation needs of small and medium-sized boiler desulfurization
As important facilities for industrial and civil heating in my country, small and medium-sized coal-fired boilers have long faced severe challenges in environmental protection. Traditional desulfurization technologies such as limestone-gypsum method have problems such as large equipment footprint, high sludge disposal cost, and secondary pollution risk. Especially for decentralized boiler rooms, the transformation is more difficult. Taking a boiler room in Yingkou, Liaoning as an example, the original wet desulfurization and dust removal system had a smoke emission concentration of up to 190mg/Nm³, and a sulfur dioxide emission concentration of over 600mg/Nm³, which is far lower than the new national standard requirements (smoke ≤80mg/Nm³, SO₂≤400mg/Nm³).
In this context, magnesium hydroxide desulfurization technology has become the preferred solution for small and medium-sized boiler transformation with its high desulfurization efficiency (95%-98%), by-product resource potential and anti-scaling characteristics. However, the traditional non-standard design leads to poor equipment adaptability and high operation and maintenance costs, and it is urgent to break the industry bottleneck through modular and standardized design.
2. Core technological breakthroughs of modular design
1. Decoupling and integration of functional units
The modular device disassembles the desulfurization system into four core modules:
Pre-dust removal module: integrated cyclone separation + bag filtration two-stage treatment, the smoke dust interception rate is increased to 99.5%, and the outlet particle concentration is stabilized below 50mg/Nm³, creating a clean reaction environment for subsequent desulfurization.
Absorption tower module: The tower body is made of fiberglass, with a three-stage cyclone spray layer and a high-efficiency demister. The liquid-gas ratio is optimized to 2.5L/m³ (the traditional process requires 5L/m³), and the system resistance is controlled within 800Pa.
Slurry circulation module: The corrosion-resistant centrifugal pump group with standardized design, combined with the intelligent pH control system, realizes the dynamic matching of magnesium hydroxide slurry concentration (8%-12% fluctuation), and the reagent utilization rate is increased by 30%.
Byproduct treatment module: integrated vacuum belt filter press + oxidation aeration tank, the purity of magnesium sulfate crystallization reaches 98%, which can be directly used as agricultural magnesium fertilizer or building material additive, achieving zero landfill of solid waste.
2. Standardized interface and fast assembly
Pipeline flange unification: flange connection standards are formulated according to DN50-DN300 classification, reducing on-site welding workload and shortening the installation cycle by 60%;
Intelligent control system embedded: PLC-based DCS system is pre-installed in standard cabinets, supports plug-and-play, and the debugging time is compressed from 7 days to 24 hours;
Container transportation: The module size is limited to 6m×2.5m×2.8m, adapted to road transportation conditions, and boiler rooms in remote areas can achieve "one week delivery and three days of production".
3. Practical cases and benefits of standardized design
Case 1: Renovation of a regional heating center in Hebei
The center centralized the renovation of 12 10t/h chain furnaces and adopted modular magnesium hydroxide desulfurization devices:
System configuration: Each boiler is equipped with an independent module group, sharing the central control platform and by-product collection system;
Operation data: SO₂ emission concentration dropped to 180mg/Nm³, annual by-product magnesium sulfate was 1,200 tons, and direct sales revenue covered 60% of operation and maintenance costs;
Economic efficiency: The total investment was reduced by 35% compared with the traditional process, the land area was reduced by 50%, and the investment recovery period was shortened to 2.8 years after obtaining local environmental protection subsidies.
Case 2: Upgrade of self-provided boiler of Southern Food Factory
For high humidity and intermittent operation conditions, modular design is optimized:
Moisture-proof and anti-corrosion upgrade: The tower coating adopts silicon carbide-epoxy resin composite material, which can withstand humidity>90% environment;
Intelligent start-stop logic: Through the flue gas flow sensor linkage system, the standby power consumption is reduced by 70%;
Byproduct resource utilization: magnesium sulfate is used as flocculant for sewage treatment in the factory area, saving 180,000 yuan in annual reagent procurement costs.
IV. Key path for the construction of standardization system
1. Materials and manufacturing standards
Corrosion-resistant material classification: Material grades are divided according to working conditions such as pH 2-12 and Cl⁻ concentration ≤20000mg/L, and SS316L stainless steel and ceramic lining composite structure are preferred;
Component life certification: It is mandatory to stipulate that the impeller life of the circulating pump is ≥20,000 hours and the demister blockage rate is <5%/year, and it has passed ISO 9001 and API 932B dual certification.
2. Intelligent operation and maintenance standards
Remote diagnosis protocol: Open Modbus RTU and OPC UA interfaces, support third-party environmental protection platform data access;
Predictive maintenance model: Based on historical data training AI algorithm, early warning of nozzle wear, slurry crystallization and other faults 14 days in advance.
3. By-product quality standards
Agricultural grade magnesium sulfate: heavy metal (As, Cd) content ≤10ppm, water insoluble matter ≤0.5%, in line with the "GB/T 20707-2023" fertilizer standard;
Industrial grade magnesium sulfate: Cl⁻≤0.01%, Fe³⁺≤0.005%, meet the purity requirements of lithium battery electrolyte additives.
V. Market promotion and industrial collaboration
1. Regional cluster application
In areas rich in magnesite resources (such as Dashiqiao, Liaoning, and Laizhou, Shandong), promote the "mine-module factory-boiler room" industrial chain collaboration model:
The mine directly supplies high-activity magnesium oxide (MgO ≥ 90%), and the transportation radius is controlled within 200km;
The modular assembly base is located nearby to reduce logistics and inventory costs;
The by-product magnesium sulfate is targeted to supply local compound fertilizer enterprises to form a regional circular economy closed loop.
2. Financial instrument empowerment
Green credit support: Commercial banks provide special loans with a 20% interest rate reduction for standardized transformation projects;
Carbon asset development: Each ton of SO₂ emission reduction can be converted into 0.8 tons of CO₂ equivalent, and the annual revenue through carbon exchange transactions exceeds 500,000 yuan/10,000 tons of standard coal boilers.
VI. Future direction of technological evolution
1. Low-carbon process integration
Pilot photovoltaic-driven slurry preparation system, reducing the energy consumption of MgO maturation from 45kWh to 28kWh per ton;
Explore hydrogen calcination regeneration technology, thermally decompose the byproduct magnesium sulfate into high-purity MgO, and achieve 80% reuse rate of absorbent.
2. Deepening of digital twin
Build a three-dimensional visualization operation and maintenance platform, map the flow field and temperature field distribution in the desulfurization tower in real time, and optimize the layout of the spray layer;
Blockchain traces the flow of magnesium sulfate to meet the EU REACH regulations and agricultural quality control certification requirements.
The deep integration of modularization and standardization is reshaping the value chain of small and medium-sized boiler desulfurization technology. When the prefabricated functional units are precisely connected like building blocks, and when the byproduct magnesium sulfate is transformed from a pollution residue to a revenue-generating resource, this transformation is not only about meeting environmental standards, but also a microcosm of the transition of traditional industries to green smart manufacturing. For small and medium-sized boiler users, choosing a modular magnesium hydroxide desulfurization device is not only an inevitable move to fulfill social responsibility, but also a strategic investment to reduce costs and increase efficiency. The implementation of each standardized equipment is writing a replicable solution for the "Battle for Blue Skies."